Deuterium permeation in polycrystalline nickel pre-implanted with nickel and helium ions

The interaction between deuterium and irradiation defects in nickel is studied using the gas-phase permeation technique. Irradiation defects were introduced using 90 keV Ni+ ions with fluences of 1014−1017 ions cm−2, or 30 keV 4He+ ions with fluences of 1015−5 × 1016 ions cm−2. Permeation results show that crystalline defects such as dislocation loops produce no measurable effect on deuterium permeation in the temperature range 370–570 K. By comparison, helium defects decrease the apparent diffusivity by four to six orders of magnitude, indicating a strong trapping effect for deuterium. These results are discussed using a simple trapping model.